From time to time, pneumatic tires require repair or replacement. To service such tires, the tire must be removed from the wheel rim. A variety of tools have been developed and utilized to facilitate the working of tires. Such tools typically comprise an elongate bar having a handle and a working end adapted to be inserted between the tire bead and wheel rim. The working end of the tool frequently has a flattened or tapered portion to facilitate insertion of the working end between the tire bead and the wheel rim.
To utilize the implement, the tool working portion is inserted manually between the bead of the tire and its associate wheel rim. Thereafter, the user applies pressure on the handle and moves a portion of the working end into contact with the wheel rim, thereby establishing the wheel rim as a fulcrum and making a lever of the tool. Pressure upon the handle causes the tool working end to engage and move a segment of the tire bead inward and allows the tire bead to be stretched over the rim by moving the tool around the periphery of the tire. In more recent years, machines have been developed which rotate the tire in conjunction with the use of the tool to alleviate the need for moving the tool. While the prior art is replete with working tools, the basic design has not changed significantly over the years. Known designs, while working well to an extent, have proven less than satisfactory in providing an optimally functional tire working implement. Some known devices remove tubeless truck tires by using separate tools for each tire bead. A first working tool is inserted between the second tire bead and the wheel rim and leverages the second bead over the rim to complete removal of the tire.
To aid in the removal process, some designs incorporate a projection that extends from the bottom of the flattened portion to create additional leverage when engaged with the wheel rim. Projections, however, carry a disadvantage in that they contact the wheel rim at a single point. Other devices use rollers as the pivot point between the tool and wheel rim. Rollers are undesirable in use because they are prone to movement during the working process and such movement can reduce the mechanical advantage provided by the tool. Still other designs use a bend in the mounting tool working end to create a pivot point. A bend is advantageous to an extent, but, as with a projection, it provides only a single point of contact with the wheel rim. With only one point of contact, the tool is prone to rocking or slipping on the rim during the tire removal procedure. Rocking or slipping can dislodge the working tool and require the user to begin the working process anew. At best, rocking or slipping necessarily causes the user to exert additional effort and concentration to maintain the working tool in its proper position.
Known working tool designs for demounting a second bead comprise a straight tool having a tip that angles downwardly from the longitudinal plane of the tool. While a downward end creates a more efficient lever, the downwardly turned tip, however, makes insertion difficult and requires inserting the tip at a sideways angle to the bead. A user will typically insert the tip between the tire bead and the wheel rim, leading with a corner of the tip, and gradually working the remainder of the tip underneath. This process is time consuming, and requires significant effort.
Also, the straight design's range of motion is limited by contact with the tread of the tire. The tread is relatively stiff and does not compress when the tool is raised to the point of contacting the tread. As a result rotation of the tool is effectively stopped. This may prevent the user from demounting the tire, or, in the least require greater effort to pry the rim free.